1. Field of the Invention
The present invention relates to a semiconductor device and more specifically to a plastic molded semiconductor device and a method for fabricating the same.
2. Description of the Prior Art
A plastic molded semiconductor device, for example, a plastic molded integrated circuit, is known and is fabricated by assembling and interconnecting a semiconductor chip on a substrate or lead frame and molding the entire structure in plastic, with the exception of the leads, to form the body of the component. In this type of fabrication, a single lead frame made from a metal ribbon and comprising a stage and leads is used, with the result that the leads do not overlap the stage on which the semiconductor chip is mounted.
Although the size of a semiconductor chip tends to be increased, the size of a semiconductor device should be a predetermined size, a row space size, or, preferably, as small as possible so that it can be packed more densely. In a semiconductor device, however, leads must be embedded in plastic in more than a fixed length in order to obtain a required pull out resistance, which limits the maximum size of a stage on which a semiconductor chip is mounted and, therefore, limits the maximum size of a semiconductor chip mounted on the stage if the size of a semiconductor device is predetermined.
Further, recent large-scale integrated circuits tend to have electrodes arranged only on two longitudinally opposed edges of a semiconductor chip. Therefore, it is difficult to form a layout of leads adopted suitable for this arrangement of electrodes, and it is particularly difficult if the width from the outer edge of a plastic body to be molded to near the stage on which a semiconductor chip is mounted is narrow.